U.S. patent application number 13/090476 was filed with the patent office on 2011-11-03 for propagating system information changes to relays.
Invention is credited to Gunnar Mildh, Jessica Ostergaard.
Application Number | 20110268014 13/090476 |
Document ID | / |
Family ID | 44858195 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110268014 |
Kind Code |
A1 |
Mildh; Gunnar ; et
al. |
November 3, 2011 |
Propagating System Information Changes to Relays
Abstract
Teachings herein include a base station for propagating system
information changes from the base station to the relay node. Upon
transmitting system information changes to the relay node, the base
station defers data transmission between the base station and the
relay node until a set time period. In many embodiments, the base
station is configured to actually apply the system information
changes during this time period, while the relay node applies the
changes before then, e.g., by applying them immediately upon
reception. The base station's deferral of data transmission until
the set time period thus ensures that data transmission does not
occur until both the base station and the relay node have applied
the pending changes. This in turn prevents radio link failure from
occurring due to use of different system parameters by the base
station and relay node.
Inventors: |
Mildh; Gunnar; (Sollentuna,
SE) ; Ostergaard; Jessica; (Stockholm, SE) |
Family ID: |
44858195 |
Appl. No.: |
13/090476 |
Filed: |
April 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61330636 |
May 3, 2010 |
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Current U.S.
Class: |
370/315 |
Current CPC
Class: |
H04W 84/047 20130101;
H04B 7/155 20130101; H04W 72/1289 20130101; H04W 24/04 20130101;
H04B 7/2606 20130101; H04W 24/02 20130101 |
Class at
Publication: |
370/315 |
International
Class: |
H04B 7/14 20060101
H04B007/14 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2011 |
SE |
PCT/SE2011/050391 |
Claims
1. A method implemented by a base station of a wireless
communication system for propagating system information changes to
a relay node that relays control signaling and data between the
base station and one or more mobile terminals, the method
comprising: sending to the relay node a message that includes
system information changes; and upon sending the message, deferring
data transmission between the base station and the relay node until
a set time period.
2. The method of claim 1, further comprising applying the system
information changes at the base station during the set time
period.
3. The method of claim 1, wherein said sending comprises sending
the message to the relay node via dedicated signaling.
4. The method of claim 1, further comprising sending a control
indicator to the relay node that directs the relay node to apply
the system information changes immediately upon receiving those
changes.
5. The method of claim 1, wherein the base station is configured to
transmit data to the relay node according to a particular time slot
configuration that specifies permissible and non-permissible time
slots during which the relay node can and cannot receive data from
the base station, respectively, and wherein said deferring
comprises deferring data transmission to the relay node until the
next permissible time slot that occurs during the set time
period.
6. The method of claim 5, wherein a time slot configuration
comprises a subframe configuration pattern.
7. The method of claim 1, wherein the base station is configured to
only apply system information changes at the start of set
modification periods that recur periodically and wherein said
deferring comprises deferring data transmission between the base
station and the relay node until at least the start of the next
modification period.
8. The method of claim 1, further comprising identifying each sent
system information change as belonging to either a first or a
second class, and wherein said deferring comprises deferring data
transmission between the base station and the relay node until the
set time period only if any of the sent system information changes
belong to the first class.
9. The method of claim 8, wherein the first class includes
fundamental system information changes that fatally disrupt radio
link connectivity between the base station and the relay node if
not applied at the base station and the relay node at substantially
the same time, and wherein the second class includes
non-fundamental system information changes.
10. A base station in a wireless communication system, the base
station comprising: an interface towards a relay node that relays
control signaling and data between the base station and one or more
mobile terminals; a system information controller configured to
send to the relay node, via said interface, a message that includes
system information changes; and a scheduler configured, upon the
system information controller sending the message, to defer data
transmission between the base station and the relay node until a
set time period.
11. The base station of claim 10, wherein the system information
controller is configured to apply the system information changes
during the set time period.
12. The base station of claim 10, wherein the system information
controller is configured to send the system information changes to
the relay node via dedicated signaling.
13. The base station of claim 10, wherein the system information
controller is further configured to send a control indicator to the
relay node that directs the relay node to apply the system
information changes immediately upon receiving those changes.
14. The base station of claim 10, wherein said interface is
configured to transmit data to the relay node according to a
particular time slot configuration that specifies permissible and
non-permissible time slots during which the relay node can and
cannot receive data from the base station, respectively, and
wherein the scheduler is configured to defer data transmission to
the relay node until the next permissible time slot that occurs
during the set time period.
15. The base station of claim 14, wherein a time slot configuration
comprises a subframe configuration pattern.
16. The base station of claim 10, wherein the system information
controller is configured to only apply system information changes
at the start of set modification periods that recur periodically,
and wherein the scheduler is configured to defer data transmission
between the base station and the relay node until at least the
start of the next modification period.
17. The base station of claim 10, wherein the system information
controller is configured to identify each sent system information
change as belonging to either a first or a second class, and
wherein the scheduler is configured to defer data transmission
between the base station and the relay node until the set time
period only if any of the sent system information changes belong to
the first class.
18. The base station of claim 17, wherein the first class includes
fundamental system information changes that fatally disrupt radio
link connectivity between the base station and the relay node if
not applied at the base station and the relay node at substantially
the same time, and wherein the second class includes
non-fundamental system information changes.
Description
RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional patent
application Ser. No. 61/330,636, filed May 3, 2010, and to
International patent application No. PCT/SE2011/050391, filed Apr.
1, 2011, each of which is incorporated by reference herein in its
entirety.
TECHNICAL FIELD
[0002] The present invention relates generally to wireless
communication systems and more particularly relates to changing
system information in wireless communication systems that support
relay nodes.
BACKGROUND
[0003] The 3rd-Generation Partnership Project (3GPP) is currently
standardizing relay nodes (RNs) for the Long Term Evolution (LTE)
radio access technology. From a radio propagation perspective, a
relay node is positioned between a base station (BS, or called an
eNodeB in the LTE standard) and one or more mobile terminals (MT,
or called user equipment, UE, in the LTE standard). This way,
communications between the base station and the mobile terminals
are relayed by the relay node.
[0004] Specifically, a relay node connects to an associated base
station using the same, standard radio link used by ordinary mobile
terminals. The relay node then provides radio access to mobile
terminals, effectively emulating a base station from the
perspective of the mobile terminals, and uses its radio link to the
base station as backhaul transport for terminal data.
[0005] While relay nodes improve system coverage and capacity, the
nodes introduce complexities to the process of propagating system
information changes throughout the system. System information
includes parameters that describe general information about the
system, including the Public Land Mobile Network (PLMN) ID, the
system bandwidth, and the like. System information also includes
parameters that describe information specific to certain cells in
the system, such as the allocation of control channels, paging
channel information, cell selection information, and so on.
[0006] Known approaches to propagating changes in system
information parameters throughout systems that do not support relay
nodes effectively ensure that a base station and its associated
mobile terminals apply the changes at the same time. In this
regard, the base station and terminals are configured to only apply
system information changes during or at the start of predefined
modification periods that recur periodically. When system
information is to be changed, the base station sends a change
notification to the terminals over a paging channel. The change
notification informs the terminals that the base station will be
broadcasting system information changes at the start of the next
modification period. When that period eventually starts, the base
station broadcasts the changes, and applies the changes itself. The
terminals immediately apply the changes upon receipt so that the
changes are applied at approximately the same time as when the base
station applies them.
[0007] Complexities occur in systems that support relay nodes
because the relay nodes may not be able to receive the change
notification sent by the base station over the paging channel.
Moreover, even if relay nodes are able to receive the change
notification, the relay nodes may still not be able to receive the
actual changes subsequently broadcasted. For example, relay nodes
may transmit and receive using the same frequency band. These
"in-band" relay nodes are therefore configured to receive
transmissions from the base station during certain time slots
(i.e., "downlink time slots"), and to transmit to the mobile
terminals during other time slots (i.e., "uplink time slots"). If
the base station transmits a change notification or actual changes
during an uplink time slot, the relay node will not receive that
notification or those changes.
[0008] Known proposals suggest transmitting system information
changes to a relay node via dedicated signaling, so that the relay
node can at least receive the changes. However, under some
circumstances, transmitting changes via dedicated signaling in this
way can cause radio link failure and/or cause unnecessary system
interference.
SUMMARY
[0009] Teachings herein include a base station that advantageously
propagates system information changes to a relay node while
preserving radio link connectivity and mitigating unnecessary
system interference. To this end, upon transmitting system
information changes to the relay node, the base station may defer
data transmission between the base station and the relay node until
a later time. In many cases explained more fully herein, this
deferral ensures that data transmission does not occur until both
the base station and the relay node have applied the pending
changes.
[0010] In one or more embodiments, the base station includes an
interface, a system information controller, and a scheduler. The
interface is towards the relay node and is thus configured to
communicate with the relay node. The system information controller
is configured to send to the relay node, via the interface, a
message that includes system information changes. System
information changes as used herein refer to changes in operational
parameters of the supporting wireless communication system (e.g.,
the system bandwidth, allocation of control channels, and the
like).
[0011] Upon the system information controller sending the message
with system information changes, the scheduler is configured to
defer data transmission between the base station and the relay node
until a set time period. In at least some embodiments, deferring
data transmission in this way entails dynamically modifying a
previously established schedule of data transmissions to or from
the relay node. For example, a data transmission previously
scheduled to occur after the sending of the system information
changes but before the set time period starts is re-scheduled by
the scheduler to occur during the set time period (e.g., at the
start of that time period, or thereafter).
[0012] As suggested above, this deferral may effectively ensure
that data transmission does not occur until both the base station
and the relay node have applied the pending changes. For example,
in many embodiments, the base station is configured to apply the
system information changes during the set time period (e.g.,
synchronously with mobile terminals in the system). The relay node,
by contrast, may apply the changes immediately upon receiving them,
which occurs before the set time period. In at least one
embodiment, for instance, the base station's system information
controller sends a control indicator to the relay node that directs
the relay node to apply the changes immediately. Or, in another
embodiment, the relay node is preconfigured to always apply system
information changes immediately upon receipt, without any regard to
control indicators received from the base station. Regardless, by
the time the set time period occurs and the base station applies
the pending changes, the relay node has already applied those
changes. Because of this, the base station's deferral of data
transmission until the set time period ensures that data
transmission does not occur until both the base station and the
relay node have applied the pending changes.
[0013] Of course, the base station may slightly decreases data
rates when it defers data transmission, albeit much less so than if
radio link failure were to occur. The base station in some
embodiments is therefore configured to only defer data transmission
if necessary to preserve radio link connectivity. Otherwise, the
base station refrains from deferring data transmission in order to
maintain data rates.
[0014] For example, in some embodiments, system information changes
that would fatally disrupt radio link connectivity if not applied
at the base station and relay node at substantially the same time
may be classified as fundamental changes, with other system
information changes being classified as non-fundamental. In this
case, the base station's system information controller is
configured to identify each sent system information change as
belonging to either a fundamental class or a non-fundamental class.
Provided with the class to which each change belongs, the scheduler
defers data transmission only if any of the sent changes belong to
the fundamental class
[0015] Of course, the present invention is not limited to the above
features and advantages. Indeed, those skilled in the art will
recognize additional features and advantages upon reading the
following detailed description, and upon viewing the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a block diagram of a wireless communication system
that includes a base station configured according to one or more
embodiments of the present invention for propagating system
information changes to a relay node.
[0017] FIG. 2 is a timeline that illustrates deferral of data
transmission by a base station according to one or more
embodiments.
[0018] FIGS. 3A-3B illustrate deferral of data transmission by a
base station that, according to one or more embodiments, transmits
data according to a time slot configuration.
[0019] FIG. 4 is a logic flow diagram that illustrates a method
implemented by a base station according to one or more embodiments
for propagating system information changes to a relay node.
DETAILED DESCRIPTION
[0020] FIG. 1 depicts a wireless communication system 10 configured
to support relay services. The system 10 includes a base station
20, a relay node 30, and one or more mobile terminals 40.
[0021] The relay node 30 is configured to relay communications
between the base station 20 and the mobile terminals 40. Relayed
communications may include control signaling as well as actual
data. Regardless, the relay node 30 receives communications from
the base station 20 over radio link 12, and relays at least some of
those communications to mobile terminals 40 over radio link 14.
Other communications (e.g., certain control signaling) received
from the base station 20 may in fact be destined for the relay node
30 itself, and therefore is not relayed.
[0022] Correspondingly, the base station 20 includes interface 22.
Interface 22 is an interface towards the relay node 30 and is
configured to communicate with the relay node 30 via radio link 12,
such as by sending control signaling and data to the relay node 30.
In this regard, the base station 20 further includes one or more
processing circuits 24 with a system information controller 26. The
system information controller 26 is configured to send control
signaling destined for the relay node 30. Specifically, the system
information controller 26 is configured to send to the relay node,
via interface 22, a message that includes system information
changes.
[0023] System information changes as used herein refer to changes
in operational parameters of the wireless communication system 10.
System information changes thus include changes in parameters that
generally describe information about the system 10, including the
Public Land Mobile Network (PLMN) ID, the system bandwidth, and the
like. System information changes also include changes in parameters
that describe information specific to certain cells in the system
10, such as the allocation of control channels, paging channel
information, cell selection information, neighboring carrier or
cell information, information regarding barring of certain
services, and so on.
[0024] Notably, the base station 20 is configured to propagate
these system information changes to the relay node 30 while
preserving radio link connectivity and/or mitigating unnecessary
system interference. To this end, the base station 20 further
includes a scheduler 28. The scheduler 28 is configured, upon the
controller 28 sending the message including system information
changes, to defer data transmission between the base station 20 and
the relay node 30 until a set time period.
[0025] In at least some embodiments, deferring data transmission in
this way entails dynamically modifying a previously established
schedule of data transmissions to or from the relay node 30. For
example, a data transmission previously scheduled to occur after
the sending of the system information changes but before the set
time period starts is re-scheduled by the scheduler 28 to occur
during the set time period (e.g., at the start of that time period,
or thereafter). FIG. 2 illustrates a simple example of these
embodiments.
[0026] At time T1 in FIG. 2, the system information controller 26
sends a message including system information changes to the relay
node 30. When this occurs, the scheduler 28 defers data
transmission between the base station 20 and the relay node 30
until a set time period P. Such entails deferring a data
transmission TX previously scheduled by the scheduler 28 to occur
at time T2. In deferring this data transmission TX, the scheduler
28 re-schedules the data transmission TX to occur as data
transmission TX' at time T3 (i.e., during the set time period
P).
[0027] FIGS. 3A-3B depict additional details of this process for
certain embodiments. In these embodiments, the base station 20 is
configured to transmit data to the relay node 30 according to a
particular time slot configuration 50. The time slot configuration
50 specifies permissible time slots (denoted by a check mark, " ")
and non-permissible time slots (denoted by an "X") during which the
relay node 30 can and cannot receive data from the base station 20,
respectively.
[0028] As shown in FIG. 3A, the scheduler 28 has previously
scheduled data transmissions to the relay node 30 to occur during
permissible time slots 52-1, 52-2, 52-3, and 52-4. But, as shown in
FIG. 3B, the system information controller 26 sends system
information changes to the relay node 30 during permissible time
slot 52-2 (in conjunction with the previously scheduled data
transmission). Correspondingly, the scheduler 28 dynamically
modifies the schedule of data transmissions so that data
transmissions previously scheduled to occur after permissible time
slot 52-2 but before the set time period P are deferred until the
set time period P. In FIG. 3B, for example, this entails deferring
the data transmission TX previously scheduled to occur during
permissible time slot 52-3 until the next permissible time slot
54-1 that occurs during the set time period P. Although not shown,
the data transmission previously scheduled to occur during
permissible time slot 52-4 would be deferred in an analogous
manner.
[0029] The example in FIGS. 3A-3B demonstrates that the particular
time at which deferred data transmissions occur during the set time
period P may depend on the time slot configuration 50 of the base
station 20. In this example, the next permissible time slot 54-1
that occurred during the set time period P was not the first time
slot that occurred during the set time period P (instead, the first
time slot was a non-permissible time slot). So, deferred data
transmissions in this example did not occur at the start of the set
time period P. But, in other embodiments, the next permissible time
slot 54-1 that occurred during the set time period P could have in
fact been the first time slot. In that case, deferred data
transmissions would actually occur at the start of the set time
period P.
[0030] Also, in at least one embodiment, the time slot
configuration 50 discussed above with respect to FIGS. 3A-3B
comprises a subframe configuration pattern. In this case, the relay
node 30 is a so-called "in-band" relay node because it uses the
same frequency for both communication with the base station 20 and
communication with the mobile terminals 40 (i.e., the same
frequency for both radio links 12 and 14). Using a single
frequency, the relay node 30 cannot use both links 12, 14 at the
same time without experiencing prohibitive levels of interference.
Thus, the base station 20 must communicate with the relay node 30
during gaps in relay-to-terminal communications. The subframe
configuration pattern provides such gaps. Also, in case the base
station 20 can communicate with some mobile terminals directly
using an interface 29 towards those terminals, the subframe
configuration pattern permits the base station 20 to at least
transmit control signaling to legacy mobile terminals that expect
such signaling in every time slot.
[0031] More particularly, during the subframe "gaps" created by the
subframe configuration pattern, the relay node 30 transmits control
signaling (e.g., cell-specific reference signals) in one or more of
the first few symbols of the subframe. The rest of the subframe is
used for data transmission between the base station 20 and the
relay node 30. Accordingly, in terms of the "permissible" and
"non-permissible" time slots discussed above with respect to FIGS.
3A-3B, the permissible time slots 52-1, 52-2, 52-3, 52-4, and 54-1
are subframe "gaps." In this context, the base station 20 thus
defers data transmission until the next subframe "gap" that occurs
during the set time period.
[0032] Regardless, in some embodiments, the scheduler's deferral
ensures that data transmission occurs only when the base station 20
has applied the system information changes. This facilitates
preservation of radio link connectivity and mitigation of
unnecessary system interference. In more detail, application of
system information changes by the base station 20 entails, in at
least some embodiments, updating one or more parameters stored at
the base station 20, e.g., in memory 25. Interface 22 may
communicate with the relay node 30 over radio link 12 in accordance
with these stored parameters. The relay node 30 may apply system
information changes in an analogous manner, e.g., by updating
parameters stored at the relay node 30. Thus, if the base station
20 and the relay node 30 apply the system information changes and
update their respective stored parameters at different times, radio
link 12 connectivity between the two may be fatally disrupted.
Moreover, use of different stored parameters may actually cause
interference to other relay nodes or mobile terminals.
[0033] Consider, for example, embodiments where the base station 20
is configured to apply the system information changes during the
set time period. The relay node 30 receives the changes before
then, and may therefore apply the changes before the base station
20. If so, data transmission attempted during this interim may fail
because the base station 20 and the relay node 30 would be using
different system parameters. This may ultimately be interpreted as
failure of the radio link 12. Accordingly, by deferring data
transmission until the set time period, the base station's
scheduler 28 ensures that data transmission does not occur until at
least the base station 20 has applied the pending changes.
[0034] In some embodiments, this also effectively ensures that data
transmission does not occur until both the base station 20 and the
relay node 30 have applied the pending changes. For example, in at
least one embodiment, the base station's system information
controller 26 is configured to send a control indicator to the
relay node 30 that directs the relay node 30 to apply the system
information changes immediately upon receiving them (which occurs
before the set time period). Or, in another embodiment, the relay
node 30 is preconfigured to always apply system information changes
immediately upon receipt, without any regard to control indicators
received from the base station 20. Regardless, by the time the set
time period occurs and the base station 20 applies the pending
changes, the relay node 30 has already applied those changes.
Because of this, the base station's deferral of data transmission
until the set time period ensures that data transmission does not
occur until both the base station 20 and the relay node 30 have
applied the pending changes.
[0035] Of course, the base station may slightly decreases data
rates when it defers data transmission, albeit much less so than if
radio link failure were to occur. The base station 20 in some
embodiments is therefore configured to only defer data transmission
if necessary to preserve radio link connectivity. Otherwise, the
base station 20 refrains from deferring data transmission in order
to maintain data rates.
[0036] In general, system information changes that would fatally
disrupt radio link connectivity if not applied at the base station
20 and relay node 30 at substantially the same time may be
classified as fundamental changes, with other system information
changes being classified as non-fundamental. Examples of
fundamental changes include cell bandwidth, control channel
allocation (e.g., Physical Uplink Control Channel, PUCCH, in LTE),
and other essential information (e.g., Random Access Channel, RACH,
in LTE). On the other hand, examples of non-fundamental changes
include uplink power control parameters, common time alignment
timer parameters, and certain cell-specific information, such as
sounding reference signal configuration. If the relay node applies
a different sounding reference signal configuration than the base
station, for instance, the relay node's transmission of a sounding
reference signal in the incorrect subframe will cause unnecessary
interference, and that sounding reference signal will not be usable
by the base station 20. But, the interference will not break the
relay node's connection to the base station 20, or cause
significant problems for the mobile terminals 40.
[0037] Thus, the system information controller 26 in some
embodiments is configured to identify each sent system information
change as belonging to either a fundamental class or a
non-fundamental class. Provided with the class to which each change
belongs, the scheduler 28 defers data transmission only if any of
the sent changes belong to the fundamental class. That is, if any
of the sent changes are fundamental and would jeopardize radio link
connectivity, the scheduler 28 defers data transmission. Otherwise,
if all of the sent changes are non-fundamental and would not
jeopardize radio link connectivity, the scheduler 28 does not defer
data transmission. This way, in systems that most often change
non-fundamental system information as opposed to fundamental system
information, the scheduler 28 most often refrains from deferring
data transmission in order to maintain data rates, while only
occasionally deferring data transmission in order to preserve radio
link connectivity.
[0038] Note that the base station's application of system
information changes during the set time period may be part of a
larger effort to apply the changes synchronously with the mobile
terminals 40. In some embodiments, for example, the set time period
is "set" in the sense that it comprises the next time period in a
series of time periods that recur with a periodicity set by the
system 10. Each of these recurring time periods is referred to
herein as a modification period. The set periodicity of
modification periods is known throughout the system 10, or at least
to the base station 20 and mobile terminals 40. Because of this,
modification periods can help coordinate synchronous application of
system information changes among the base station 20 and the mobile
terminals 40.
[0039] Indeed, in various embodiments, both the base station 20 and
the mobile terminals 40 are configured to apply the system
information changes at the start of the next modification period.
Since the base station 20 is committed to the mobile terminals 40
in this way, it cannot simply apply the changes immediately upon
sending them to the relay node 30 (in an effort to instead apply
the changes synchronously with the relay node 30). According to
embodiments herein, then, because the base station 20 cannot apply
the system information changes synchronously with the relay node
30, the base station 20 instead ensures that data transmission does
not occur until both the base station 20 and the relay node 30 have
applied the system information changes. That is, the base station
20 defers data transmission until at least the start of the next
modification period.
[0040] Those skilled in the art will of course appreciate that the
above embodiments have been described as non-limiting examples, and
have been simplified in many respects for ease of illustration. For
instance, descriptions above have generalized communications
between the base station 20 and the relay node 30 as simply
occurring over a radio link 12. Likewise descriptions above have
generalized communications between the relay node 30 and mobile
terminals 40 as occurring over radio link 14. As suggested in some
embodiments, though, the relay node 30 uses the same frequency for
both of these radio links 12, 14. That is, the relay node 30
comprises an "in-band" relay node. In this case, much of the
communication discussed above between the base station 20 and the
relay node 30 may occur through dedicated signaling (e.g., the
system information changes, data transmissions, and, where
applicable, control indicators are communicated via dedicated
signaling).
[0041] Also, the above embodiments have not been described in the
context of any particular type of wireless communication system. In
this regard, no particular communication interface standard is
necessary for practicing the present invention. That is, the
wireless communication system 10 may be any one of a number of
standardized system implementations that support relaying of
communications between a base station and mobile terminals via a
relay node. As one particular example, the system 10 may implement
Long Term Evolution (LTE) or LTE-Advanced standards. In this case,
the base station 20 may be referred to as an evolved Node-B, or
eNB, the mobile terminals 40 may be referred to as user equipment,
or UE, and the relay node 30 may otherwise conform to LTE standards
specified in a technical report titled "3rd Generation Partnership
Project; Technical Specification Group Radio Access Network;
Evolved Universal Terrestrial Radio Access (E-UTRA); Relay
architectures for E-UTRA (LTE-Advanced); (Release 9)," 3GPP TR
36.806, v. 9.0.0 (March 2010). System information may thus need to
change, to name just a few examples: (1) when the base station 20
starts a new MBSFN service requiring the allocation of a specific
MBSFN subframe allocation that cannot be used by other services;
(2) when the system 10 is congested and the base station 20 needs
to bar some services or users from accessing the system 10; or (3)
when the base station 20 needs to increase or decrease the capacity
of some control channel (e.g., the Random Access Channel RACH, or
the Physical Uplink Control Channel, PUCCH).
[0042] With the above described modifications and variations in
mind, those skilled in the art will understand that the base
station 20 generally performs the processing illustrated in FIG. 4
for propagating system information changes to the relay node 30. As
shown in FIG. 4, processing includes sending to the relay node 30 a
message that includes system information changes (Block 100).
Processing further includes, upon sending the message, deferring
data transmission between the base station 20 and the relay node 30
until a set time period (Block 110).
[0043] Those skilled in the art will also appreciate that the
various "circuits" described may refer to a combination of analog
and digital circuits, and/or one or more processors configured with
software stored in memory 25 and/or firmware stored in memory 25
that, when executed by the one or more processors, perform as
described above. One or more of these processors, as well as the
other digital hardware, may be included in a single
application-specific integrated circuit (ASIC), or several
processors and various digital hardware may be distributed among
several separate components, whether individually packaged or
assembled into a system-on-a-chip (SoC).
[0044] Thus, those skilled in the art will recognize that the
present invention may be carried out in other ways than those
specifically set forth herein without departing from essential
characteristics of the invention. The present embodiments are thus
to be considered in all respects as illustrative and not
restrictive, and all changes coming within the meaning and
equivalency range of the appended claims are intended to be
embraced therein.
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